An imaging device in which an imaging element such as a CCD or a CMOS is mounted on a substrate for mounting an imaging element has been known for some time. The substrate for mounting an imaging element is formed of an insulating base having an insulation layer, the imaging element is mounted thereon, and the substrate is sealed using a cover formed of, for example, an optical filter, glass, or crystal. An imaging device is known in which a lens holder to which a plurality of lenses are attached is joined to the substrate for mounting an imaging element on which an imaging element is mounted and that has been sealed by a cover, and an optical distance is varied by varying the positions of the plurality of lenses. (For example, see Patent Document 1.)
Meanwhile, in such an imaging module, a region between the plurality of lenses and the cover and a region between the cover and the imaging element are each sealed.